Mine roof supports



Oct. 20,. 1970 J. w. SEDDON ET MINE ROOF SUPPORTS 5 Sheets-Sheet 1 Filed Nov. 25, 1968 OW m m \w .QWm M m m w 5 \&\ & \WL. E Q 5 N Y Q \K H INVENTORz JEFFREY w.- seoom J'AcK W. BELL B Oct. 20, 1970 J. W. SEDDON ET AL MINE ROOF SUPPORTS 5 Sh.ets-Sheet Filed Nov. 25, 1968 mvsmoa; JEFFREY w. sEpnoN BY r Y JACK ,W. 8ELL Ace.

Oct. 20, 1970. J, w, SEDDON E1- AL 3,534,559

MINE ROOF SUPPORTS Filed Nov. 25, 1968 I |NVENTOR: JEFFREY Mae-Dom JACK w. BELL I Wgctn.

5 Sheets-Sheet 4.

Oct. 20, 1970 w, SEDDON ET AL v $534,559

MINE ROOF SUPPORTS 5 Sheets-Sheet Filed Nov. 25, 1968 mvemom M- SEDDoN J'AcK w. BELL Z F 3,534,559 MINE ROOF SUPPGRTS Jefirey William Seddon, Wrightington, and Jack Wallwork Bell, Garstang, Preston, England, assignors to Gnliick Limited, Wigan, Lancashire, England, a British company Filed Nov. 25, 1968, Ser. No. 778,642 Claims priority, application Great Britain, Jan. 17, 1968, 2,478/68 Int. Cl. E21d 15/44 US. CI. 61-45 11 Claims ABSCT OF THE DISCLOSURE A mine roof support has an extensible and retractable roof-supporting member or bar which is extended and retracted to positions of maximum and minimum extension and to positions therebetween by means of a pressurefiuid ram, a Wedge device being provided for setting and securing said roof-supporting member against a mine roof or releasing it therefrom at any such position. The pressure-fluid ram may also operate said wedge device.

This invention is for improvements in or relating to mine roof supports.

In the longwall method of mining, under certain geological roof conditions, there is a tendency for material to fall from the unsupported roof between the roof supports and mineral-bearing face after passage of the cutting or other mineral-winning machine. To minimise this fall of material it is often the practice to provide a supporting bar extendable from the main roof support and which is set immediately after the passage of the cutting machine and prior to the advance of the main roof support.

This extendable roof supporting bar is often manually operable. An example of such a manually operable extension bar is described in our British patent specification No. 977,503. Alternatively, the extendable supporting bar may be operated by a ram means as described, for example, in the specification of our British Pat. No. 1,061,071.

Heretofore the return of the extendable supporting bar to its initial position in the main roof support has been dependent upon the release of the latter from between floor and roof, the load on the extendable bar having made it impossible to release the wedge or locking means for the bar, described for example, in our specification No. 977,503 so as to enable the bar to be adjusted without releasing the support. Furthermore, to retract the bar from its extended position has required the operator to work over the moving face conveyor. This can be dangerous.

SUMMARY OF THE INVENTION According to the present invention, there is provided a mine roof support comprising a floor-engaging base, hydraulically extensible prop means mounted on said base, a roof-engaging srtucture mounted on said prop means for application thereby to a mine roof for the support thereof, a roof-supporting member, means carrying said roof-supporting member on said roof-engaging structure for forward and rearward extension and retraction respectively relatively thereto, to and between positions of maximum extension and retraction, a pressure-fluid ram device connected between the roof-engaging structure and the roof-supporting member and operable for the extension and retraction of the latter, setting means for applying an upward force to the roof-supporting member to set it in roof-supporting condition against a roof, and a pressure-fluid ram device operable to move said setting means between setting and release positions for the roof-supporting member.

Patented Get. 20, 1970 Means may be provided for rendering the extensible roof-supporting bar yielding or nonyielding independently of the supporting members (hydraulic legs or props) of the main support unit.

Two particular embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a side elevation, partially in section, of a roof support with the extensible and retractable roof-supporting bar in its retracted position,

FIG. 2 is a plan view of FIG. 1,

FIG. 3 is a view similar to FIG. 1 but with the roofsupporting bar extended,

FIG. 4 is a diagrammatic view of a hydraulic ram, incorporated in the support shown in FIGS. 1, 2 and 3, for extending, retracting and setting the roof-bar,

FIG. 5 is a load-diagram of the extensible roof-bar,

FIG. 6 is a fragmentary end view of a resilient yieldable member which may be embodied in the support,

FIG. 7 is a fragmentary side elevation of the resilient yieldable member shown in FIG. 6, and

FIG. 8 shows in side elevation the second embodiment of the invention.

The roof support as shown in the drawings has a roofsupporting canopy 10 supported on hydraulic props or legs 11 mounted in a base 11a. A hydraulic ram 11b is mounted in the base 11a and serves to push over a mineral face conveyor and then advance the support, in the well known way, as extraction of the mineral from the face proceeds.

An extendable and retractable roof-supporting bar 12 is provided on opposite sides with trunnions 14 which run in slots 13 provided in the canopy 10 so as to guide the bar 12 during its extension and retraction between the limbs ltla and 10b of the canopy.

A ram 15 is supported from the underside of the canopy 10 by means of brackets 16, the ram having trunnions 17 which slide freely in inclined slots 18 in said brackets.

The ram 15 has opposed pistons 15a and 15b (see FIG. 4) one of which is provided with a piston rod 19 for extending and retracting the bar 12 relatively to the canopy 10 and the other of which has a piston rod 20 adapted to operate a setting and securing means 21 for the bar 12. The setting means 21 has an inclined face and is adapted to be inserted, wedge fashion, between the canopy 10 and an inclined face 22 at the rear of the bar 12.

Referring now to FIG. 4, it will be noted that the ram 15 has an inlet for pressure-fluid at 23 for the retraction of the piston rod 19, an inlet at 24 for pressurefluid for the retraction of the piston rod 20 and a further pressure-fluid inlet 25, through the piston rod 20, for the introduction of pressure-fluid between the two pistons whereby they may be driven apart.

In the force diagram, FIG. 5, F is the fulcrum (14) of the extnsible bar 12, T indicates the tip-loading on the bar, R the resisting force and alpha the wedge angle of the setting means 21.

The yielding device shown in FIGS. 6 and 7, which may be incorporated in the support above described, is in the form of a bowed leaf-spring 26 attached or loosely anchored to the roof-bar 12 by means of a stud 27 and bearing slidably on the setting means or wedge 21 which is slotted to receive the rear end of the bar 12.

Assuming that the canopy 10 is set to the roof by application of a force by the hydraulic legs or props 11, the extensible roof-bar 12 is advanced to the face, from the fully retracted nonset condition shown in FIG. 1, by opening the line 23 to exhaust, closing the line 24 and introducing pressure-fluid through the pressure line 25. This advances the bar 12 relative to the cylinder 15, which is held in the direction of the piston movement. When the desired extension (e.g., 6 inches) of the bar 12 has been reached the pressure line 23 is closed, the line 25 opened to exhaust and fluid under pressure is introduced into the cylinder via the line 24. Under the influence of this pressurefluid the piston rod is moved in the direction of advance of the bar 12 and forces the setting means 21 between the inclined face 22 of the roof-bar 12 (or of the side edges of the spring 26) and the underside of the canopy 10. Continuation of this movement of the piston rod 20 turns the roof-bar 12 about its trunnions 17 to a position where the upper surface of the bar makes contact with the mine roof. Thus, the roof-bar 12 is set and held against the roof for the support thereof.

To release the bar 12 from the roof either prior to cffecting a further movement thereof towards the face or before the bar is to be retracted, the lines 23 and 24 are put to exhaust and pressure-fluid is introduced between the pistons via the line 25. The bar can then be further advanced by opening the line 23 to exhaust, closing the line 24 and introducing pressure-fluid through the pressure line 25. If, on the other hand, the bar 12 after being released from the roof is to be retracted, pressure-fluid is A introduced into the cylinder via the line 23, the remaining lines 24 and 25 being opened to exhaust.

By providing the leaf-spring 26 between the setting means 21 and the stud 27 attached to the roof-bar 12, the load carried by the roof-bar is limited as compared with the load which the main support 10, 11 will carry. In other words, as the roof-bar 12 falls below the level or upper face of the canopy 10, any increase in load is taken by the canopy.

If it is desired that the extension bar 12 should yield when the tip load T (FIG. 5) exceeds a certain magnitude the angle alpha is increased. This has the effect that the resistance R to the load, when the bar pivots about the fulcrum F (trunnions. 17) acts along the cylinder 15 via the piston rod 20. A pressure relief valve 24a is introduced into the pressure-fluid line 24. This valve will yield if the pressure induced by the action of the tip load T and the wedge angle alpha exceeds a predetermined amount.

The support shown in FIG. 8 is similar in several respects to that already described with reference to FIGS. 1 to 7 and where applicable like reference numerals have been used to designate like parts. In the embodiment shown in FIG. 8, however, the roof-bar 12 is extended and retracted by a ram 28 and is set to the roof by a separate ram 29 supported from the canopy 12 by a bracket or hanger 30. The circuit to the ram 29 may have a pressure relief valve incorporated in it so that it will yield at a predetermined load on the roof-bar 12. Instead of arranging for the ram 29 to act on the forward part of the roof-bar it may be arranged to act on the rear of the bar in which case it will be inverted with respect to the position shown in FIG. 8. Furthermore, the ram 29 may act directly on the bar as shown in FIG. 8 or indirectly, e.g., through a wedge means.

It will be appreciated that the above-described embodiments of the invention achieve the object of applying a load to the roof in advance of the main roof support and this load can be applied to the roof at any position between the limits of full extension and retraction of the roof-bar.

Instead of slidably mounting the extendable roof-bar 12 in the canopy 10 it may be slidably mounted in an extension bar (e.g., a cantilever extension bar) pivotally attached or secured to the canopy and projecting forwardly therefrom.

We claim:

1. A mine roof support comprising a floor engaging base, hydraulically extensible prop means mounted on said base, a roof-engaging structure mounted on said prop means for application thereby to a mine roof for the support thereof, a roof-supporting member, means carrying said roof-supporting member on said roof-engaging structure for forward and rearward extension and retraction, respectively, relatively thereto, to and between positions of maximum extension and retraction, a pressure-fluid ram device connected between the roof-engaging structure and the roof-supporting member and operable for the extension and retraction of the latter, setting means for applying an upward force to the roof-supporting member to set it in roof-supporting condition against a roof, and a pressure-fluid ram device operable to move said setting means between setting and release positions for the roof-supporting member.

2. A mine roof support as claimed in claim 1 wherein the roof-supporting member has laterally projecting members by which it is supported in guide means in the roofengaging structure of the support for extension and retraction relatively thereto.

3. A mine roof support as claimed in claim 1 wherein the pressure-fluid ram for the extension and retraction of the roof-supporting member, is provided with laterally projecting members positioned in brackets on the roomengaging structure of the support whereby said ram is supported from said roof-engaging structure.

4. A mine roof support as claimed in claim 3 wherein said brackets have inclined slots in which the laterally projecting members of the ram are slidably located.

5. A mine roof support as claimed in claim 1 wherein said setting means for the roof-supporting member is a wedge device positioned between said roof-supporting member and the roof-engaging structure of the support.

6. A mine roof support as claimed in claim 1 wherein a resilient device is located between the roof-supporting member and the setting and securing means therefor.

7. A mine roof support as claimed in claim 5 wherein a bowed spring is attached to the roof-supporting member and bears on said wedge so that the force for setting and securing the roof-supporting member is applied thereto through said spring and the roof-supporting member can be depressed relatively to the roof-engaging structure of the support against the action of said spring.

8. A mine roof support as claimed in claim 1 wherein a pressure-fluid device for the extension and retraction of the roof-supporting member and for actuating the setting means therefor has a common cylinder with opposed pistons one piston being operatively connected to the roofsupporting member and the other to the setting means therefor.

9. A mine roof support as claimed in claim 1 wherein the setting means for the roof-supporting member is a wedge which engages an inclined face of said member .the angle of said inclined face being selected according to the tip load under which the roof-supporting member is required to yield.

10. A mine roof support as claimed in claim 1 wherein the setting means for the roof-supporting member is operated by a pressure-fluid ram and a pressure relief valve is provided in the pressure-fluid circuit of said ram.

11. A mine roof support comprising a floor-engaging base, hydraulically extensible prop means mounted on said base, a roof-engaging structure mounted on said prop means for application thereby to a mine roof for the support thereof, a roof-supporting member pivotally supported by said roof-engaging structure and mounted on said roof-engaging structure for forward and rearward extension and retraction with respect thereto between positions of maximum extension and retraction, means for extending and retracting said roof-supporting member with respect to said roof-engaging structure, setting means for applying a downward force to one portion of said roof-supporting member tending to cause pivotal movement of said roof-supporting member and movement of another portion of the roof-supporting member upwardly to set it in roof-supporting condition against a roof, and means for moving said setting means between setting and release positions for the roof-supporting member.

(References on following page) References Cited UNITED 6 FOREIGN PATENTS 856,720 12/ 1960 Great Britain. 1,091,602 11/1967 Great Britain.

STATES PATENTS Seddon 1,467,272 12/1966 France,

Hemard 61451 5 1.482,298 4/1967 France.

Jackson 6145.2

Farr 1 45 2 DENNIS L. TAYLOR, Primary Examiner AdCOCk et a1. 61-452 US. Cl. X.R Andrews 6145.2 241;...357 

